And McDonalds was a treat, not a staple.
We were always allowed to have as much food as we wanted at dinner in my family. But not only was it not McDonalds, we were pretty much tossed out the door on Saturday morning and expected to not come home until lunch. When we got home from school(usually walking), we generally dropped our bags and headed right back out to run around the neighborhood with the other kids. Sedentary activities like homework were done after dinner.
We are eating worse, no doubt. But IMO if we were as active as we were then, the percentage of people who would be obese would be far lower.
Food quantity may have changed SOME in that we snack more than we did.
Food quality has dropped.
But I think the biggest factor is that now, starting in childhood, entertainment is GENERALLY sedentary. Kids are overweight and under-active before they even start school.